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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* div,p,h1{
            background-color:yellow;
    } */
     div,.box,h1{
        background-color:yellow;
     }
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<body>
    <div>
        111
        <p>222</p>
    </div>
    <p>222</p>
    <p class="box">222</p>
    <h1>333</h1>
</body>
</html>